PS- 1.3
Scientific Measurements
Bad Joke…..
 Why
did the bottle insist on
being at the front of the shelf?
Because
it was a
liter, not
a follower!
Why was a system needed?
Long ago, parts of
the human body
were often used as
units of measure.
 Egyptian “cubit”
was the length
from your elbow to
the tip of your
middle finger.

 The
length of the
kings foot or the
distance from the
tip of his nose to
his fingertips
were common
units of
measurement.
See any obvious problems with this
line of thought?

Different from country to country

Existing measurements would change
each time a new king was crowned

Different from body part to body part
 The
metric system was
created with the purpose of
establishing a universal
system of measurement that
could easily be used by people
all over the world regardless
of their country of origin.
Metric System Facts
Developed by the French in late 1700s
and was officially adopted in 1790.
 Named “Le Systeme International
d’Unites”; Abbreviated SI
 Was initially forced on all countries.
 The option for people to use the metric
system or not in the US became legal in
1866.

Metric System Facts Cont’d:

USA opted out of using the system.

USA is the only technologically advanced
country NOT using the Metric System as
it’s main system of measurement; Still
using the English System which is a
combo

Especially important to scientists
Metric System Facts Cont’d:

Decimal based system
~ What the heck does that mean?

It’s based on powers of 10, so it is very
simple to use
The Metric units most often used
by average people are….
Meter: measures length
 Second: measures time
 Gram: measures mass
 Liter: measures volume
 Degree Celsius: measures temperature
YOU WILL SEE THIS AGAIN!!

Regardless
of the
unit, the entire metric
system uses the same
prefixes.
Most common prefixes
Kilo – 1000
Deci – 1/10 or 0.1
 Hecto – 100
Centi – 1/100 or 0.01
 Deka – 10
Milli – 1/1000 0r 0.001
 Meter/gram/liter – 1

“King Henry’s Daughter Usually Drinks Chocolate Milk”
Length
 Length
 The
is the distance between 2
points
SI base unit for length is the
meter
Length
 We
use rulers
or meter sticks
to find the
length of
objects.
Mass
 Mass
is the amount of matter that
makes up an object.
 The SI unit for mass is the gram.
 The mass of an object will not
change unless we add or subtract
matter from it.
Mass
A golf ball and a ping pong ball are the
same size, but the golf ball has a lot more
matter in it.

Which has more mass?
~the golf ball has more mass
Mass

A paper clip has a mass of about one
gram

Remember: the mass of an object will not
change unless we add or subtract matter
from it.
Measuring Mass
We will use a triple beam balance scale to
measure mass.
Gravity pulls equally on both sides of a balance
scale, so you will get the same mass no matter
what planet you are on.


Weight

Weight is a measure of the force of gravity
on an object.

The SI unit for weight is the Newton (N).

The English unit for weight is the pound
Gravity

Gravity is the force of attraction between
any two objects with mass.

Gravity depends on 2 things:
Distance and Mass
Gravity

More distance = less gravity= less weight

Less distance = more gravity = more
weight

More mass = more gravity = more weight

Less mass = less gravity = less weight
Weight vs Mass
Jill
Earth
Moon
Jupiter
Orbit
Gravity
1 gravity
1/6th
gravity
Mass
30 kg
30 kg
30 kg
30 kg
Weight
300 N
50 N
750 N
0N
2.5
0 gravity
gravities
Jill
Gravity
Earth
1 gravity
Mass
Weight
30 kg
300 N
Moon
1/6th
gravity
30 kg
50 N
Jupiter
Orbit
2.5
0 gravity
gravities
30 kg
30 kg
750 N
0N
** Notice that Jill’s mass never changes**
Jill is a 30 kg little girl no matter where she
goes or what planet she is on.
Volume
Volume is the
amount of space
contained in an
object.
 We can find the
volume of box
shapes with this
formula

V= L x W x H
Volume Cont’d…

In the case of box shapes, the units would
be cubic centimeters (cm³).

So, a box that is 2cm x 3cm x 5cm would
have a volume of……
30 cm³
Base Units
 The
base unit for
volume is the
Liter.
 We measure
volume with a
graduated
cylinder.
Graduated Cylinders


Liquids form curved,
upper surfaces when
poured into graduated
cylinders (sticks to the
sides)
To correctly read the
volume, read the
bottom of the curve
called the meniscus
Liquid Volume
When the metric system was created, they
decided that 1 cm³ of water would equal 1
milliliter of water.
 That 1ml of water would have a mass of
one gram.
 1cm³ water = 1ml water = 1 gram of water

Water Displacement
 You
can use
water
displacement to
find the volume
of objects that
are not box
shaped.
Water Displacement

We can put water in a
graduated cylinder. If
a rock causes the
level to rise from 7 ml
to 9 ml, the rock must
have a volume of 2ml.
Water Mass and Volume
Remember:
1 cm³ = 1 ml = 1 g
 What would be the mass of 50 ml of
water?
50 grams
 How many milliliters would you have if you
were given 23 cm³ of water?

23 ml
Density

Density is the amount of matter (mass)
compared to the amount of space
(volume) an object occupies.

We will measure mass in grams and
volume in ml or cm³
Density Formula

Density is mass divided by volume
Density = mass / volume

Remember: all fractions are division
problems
Density Triangle



Cover the property
you are trying to find,
and do what is left.
To find density, cover
the word density.
You have mass over
volume left. So divide
mass by volume to
find density
Density Triangle

To find mass, you
cover the word
mass and do what
is left.

You have density x
volume left
Density Triangle
To find volume,
cover volume.
 You have mass
over density left, so
you divide mass by
density to find
volume

Water and Density
Since 1 gram of water has a volume of 1
ml, then the density of water will always be
1 g/ml.
 Ex: A kg of water will have a volume of
1000 ml, so it’s density will be 1 g/ml.

1000g/1000ml = 1 g/ml
Floating vs Sinking
Floating vs Sinking
 Remember:
density of water is 1
g/ml
 Less
dense materials will float on
top of more dense materials.
Floating and Sinking

Objects with a density of less than 1 g/ml
will float on top of water.

Objects with a density greater than 1 g/ml
will sink in water.
Neutral Buoyancy


Objects with a density
= to the density of
water will float in mid
water, at whatever
level you place the
object
Fish and submarines
control their depth by
changing their density
Titanic sails the ocean blue
Titanic makes it’s maiden voyage.
 What is the density of this enormous, steel
hulled ship, dull of machinery, coal, people
and all sorts of heavy things?
~It’s floating, so we know that it’s density
has to be less than 1 g/ml.
 How can that be?
~It is a hollow vessel that is full of air.

Wreck of the Titanic
The denser the ship
became, the lower it
settled into the water.
 What is the density of
the ship resting on the
ocean floor?
~must be over 1 g/ml to
have gone below the
surface

Review



How much does the prefix Hecto- represent?
~ 100
What is the SI unit for measuring length?
~ meter
What 2 things does the force of gravity depend
on?
~ mass and distance
Review
What are the 2 units that volume can be
measured in?
~ cm³ for box shapes
~ml for liquids
 What is the density of water?
~ 1 g/ml


Dimensional Analysis is a way to convert
measurements between different units to
help compare them.
BUT First, we will practice the easy
way…moving the decimal or the
“ladder method”
KHD U DCM
 Kilo Hecto Deka UNIT (m, l, g) Deci Centi Milli

Ladder Method
1
2
KILO
1000
Units
3
HECTO
100
Units
DEKA
10
Units
DECI
0.1
Unit
Meters
Liters
Grams
How do you use the “ladder” method?
1st – Determine your starting point.
2nd – Count the “jumps” to your ending point.
3rd – Move the decimal the same number of
jumps in the same direction.
CENTI
0.01
Unit
MILLI
0.001
Unit
4 km = _________ m
Starting Point
Ending Point
How many jumps does it take?
4. __. __. __. = 4000 m
1
2
3
Conversion Practice
Try these conversions using the ladder method.
1000 mg = _______ g
14 km = _______ m
1 L = _______ mL
109 g = _______ kg
160 cm = _______ mm
250 m = _______ km
Metric Conversion Challenge
Write the correct abbreviation for each metric unit.
1) Kilogram _____
4) Milliliter _____
7) Kilometer _____
2) Meter _____
5) Millimeter _____
8) Centimeter _____
3) Gram _____
6) Liter _____
9) Milligram _____
Try these conversions, using the ladder method.
10) 2000 mg = _______ g
15) 5 L = _______ mL
20) 16 cm = _______ mm
11) 104 km = _______ m
16) 198 g = _______ kg
21) 2500 m = _______ km
12) 480 cm = _____ m
17) 75 mL = _____ L
13) 5.6 kg = _____ g
14) 8 mm = _____ cm
18) 50 cm = _____ m
19) 5.6 m = _____ cm
22) 65 g = _____ mg
23) 6.3 cm = _____ mm
24) 120 mg = _____ g
Dimensional Analysis
WHAT YOU WANT
___________________
WHAT YOU HAVE

Dimensional analysis is also called the
factor-label method of problem solving. It
is a way of setting up a problem in a
constant fashion that breaks the problem
down into simple steps. Each step is a
ratio that must equal 1, thus canceling out
some preceding unit.
Examples
1.
11 mm = ______ cm
2.
261 g = _______ kg
3.
9474 mm = _______ cm
Precision vs. Accuracy
Precision is the
amount of detail in
measurements, or
how closely two or
more
measurements
agree.
Precision vs. Accuracy
Accuracy is how close a measurement is to
the actual or accepted value for that
measurement.
Practice